15. The following are elements EXCEPT a carbon c. silicon b.magnesium d. water 16. What would be the concentration of a solution made by mixing 20g of rice grains and 100mL of water? a. 12% c. 17% b. 15% d. 20% 17. The following are compounds EXCEPT a. carbon C. sugar b. salt d. water 18. What would be the concentration of a solution made by mixing 30g of sugar and 50mL of water? a. 25% b. 28% d. 38% c. 35% 19. These are forms of matter that have definite and unchanging chemical composition a. atoms C. matter b. elements d. pure substances a 20. It is a homogenous mixture consisted of a solute and solvent. a. element c. solutions b.compound d supersaturated​